Electroplated hard chromium (EHC) is widely coated onto parts to provide resistance to corrosion, wear and impact. The electroplating process, however, has significant health and environmental impacts. Air emissions during the electroplating process contain hexavalent chromium (Cr+6) - a known carcinogen, furthermore the process is energy intensive and generates hazardous waste. Because of health and environmental issues related to hard chromium plating, there have been several efforts to find alternatives. One of the more efficient technologies among the substitutes is High Velocity Oxy-Fuel (HVOF) thermal spraying. This technology is commercially available today, with a major commercial opportunity in aerospace applications. In this paper, we therefore compare the life cycle environmental footprints of hard chromium and HVOF coatings for aircraft landing gear. Our results indicate that from an environmental perspective, HVOF spraying is generally preferable to EHC plating, with 5-10 times lower human health impacts and 30-50 times lower ecosystem impacts. However, in terms of resource consumption, the processes have similar impact profiles with EHC plating having a potential for lower impact on resources in areas with a significant share of renewable electricity.

Electroplated chromium improves corrosion resistance while providing resistance to wear, fatigue and impact. However, hard chromium plating uses chromic acid, which releases fumes containing carcinogenic chromium +6 ions into air during the process. Therefore, numerous efforts have been carried out worldwide in the last decade to develop alternatives and several applications and processes were validated, among which trivalent chromium plating, electroless nickel and nickel alloy coatings, micro-welding, PVD, CVD, and thermal spraying. Nevertheless, these finishing processes have impacts on human health, ecosystems and resources. In this work, a Life-cycle assessment (LCA) methodology based on Eco-indicators 99 was used to compare the environmental impacts and benefits of thermal spraying (including APS- and HVOF-sprayed WC-Co coatings and TWEA- and APS-sprayed hard steel coatings) to conventional chromium plating.